It is known that certain pharmacologically active ingredients are extremely difficult to manufacture in tablet form due to the physical nature of the active compound itself. For example, many drugs which when utilized in free base form, i.e., not in salt form, e.g. atenolol, nadolol, salbutamol, chlordiazepoxide, temazepam, diazepam, sulpiride, d-sotalol, d-L-sotalol and the like, are prone to many undesirable tabletting problems including poor compression and dissolution properties, high lubricant requirement, formation of soft granules and "sticking" which refers to the film-forming adherence phenomenon wherein the compound adheres to tablet punches and other manufacturing apparatus. These problems can result in soft tablets of high friability and tablets of inelegant appearance due to loss of material to punch surfaces. Attempting to reduce the compression problems by increasing compression forces in the tablet press can result in high disintegration times and slow drug release which may compromise bioavailability. In all instances so far discussed high ejection forces are needed to remove tablets from dies which can result in inelegant product and machine wear.
Increasing the level of certain excipient materials to compensate for these phenomena is not without difficulties. For example, increasing the level of hydrophobic tablet lubricants to reduce ejection forces and adhesion, e.g. magnesium stearate, decreases the attainable tablet hardness which in turn can result in poor handling properties and a decrease in the rate of drug release. Attempts to counter the decreased hardness with higher compression forces have given way to retardation of the tablet disintegration. Higher ratios of lubricant-to-drug can be provided without adversely affecting tablet hardness by proportionally increasing the levels of all of the other ingredients, except the drug itself. However, this results in a substantial increase in tablet size which is not at all desirable as this might compromise patient compliance.